Semiconductor component with marginal region

ABSTRACT

A semiconductor wafer is disclosed. One embodiment provides at least two semiconductor components each having an active region, and wherein at least one zone composed of porous material is arranged between the active regions of the semiconductor components.

CROSS-REFERENCE TO RELATED APPLICATIONS

This Utility Patent Application is a divisional application of U.S.application Ser. No. 12/543,995, filed Aug. 19, 2009, and claimspriority to German Patent Application No. DE 10 2008 038 342.2 filed onAug. 19, 2008, which are both incorporated herein by reference.

BACKGROUND

The invention relates to a semiconductor component having a marginalregion, to a semiconductor wafer having a zone composed of porousmaterial, and to a method for singulating semiconductor components froma semiconductor wafer.

In the production of semiconductor components, during the singulation ofthe chips, for example by sawing or laser treatment from a semiconductorwafer, cracks can arise in the silicon which advance right into theactive region of the semiconductor components. Moreover, duringsubsequent processing of the semiconductor components, such as duringsoldering for example, heavy metals, such as copper for example, canindiffuse into the electrically active region of the semiconductorcomponents via the sawing edge. This leads in each case to an impairmentof the electrical properties of the semiconductor component.

The effects of crack production mentioned during singulation can atpresent only be reduced by using a sufficient safety distance betweenthe separating edge and the electrically active region of thesemiconductor component. However, the area utilization of asemiconductor wafer is significantly reduced and the indiffusion ofcontaminating elements cannot be significantly prevented.

For these and other reasons, there is a need for the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a schematic plan view of an exemplary embodiment of asemiconductor component with a zone composed of porous material in themarginal region.

FIG. 2 illustrates a schematic cross-sectional view of an exemplaryembodiment of a semiconductor component with a zone composed of porousmaterial in the marginal region.

FIG. 3 illustrates a schematic plan view of a further exemplaryembodiment of a semiconductor component with a zone composed of porousmaterial in the marginal region.

FIG. 4 illustrates a schematic cross-sectional view of an exemplaryembodiment of a semiconductor wafer with zones composed of porousmaterial between the active regions of semiconductor components.

FIG. 5 illustrates a schematic plan view of an exemplary embodiment of asemiconductor wafer with zones composed of porous material between theactive regions of semiconductor components and with separating zonesbetween the semiconductor components.

FIG. 6 illustrates a schematic cross-sectional view of an exemplaryembodiment of a separating zone in a zone composed of porous material ofa semiconductor wafer.

FIG. 7 illustrates a schematic cross-sectional view of an exemplaryembodiment of a semiconductor wafer with a separating zone in a zonecomposed of porous material.

FIG. 8 illustrates a schematic cross-sectional view of an exemplaryembodiment of a semiconductor wafer with a separating zone between twozones composed of porous material.

FIG. 9 illustrates a schematic cross-sectional view of an exemplaryembodiment of a semiconductor wafer with a separating zone between twozones composed of porous material.

FIG. 10 illustrates a schematic cross-sectional view of an exemplaryembodiment of a semiconductor wafer with additional zones composed ofporous material.

DETAILED DESCRIPTION

Embodiment are explained in more detail below, with reference to theaccompanying figures. However, the invention is not restricted to theembodiments specifically described, but rather can be modified andaltered in a suitable manner. It lies within the scope of the inventionto suitably combine individual features and feature combinations of oneembodiment with features and feature combinations of another embodimentin order to arrive at further embodiments according to the invention.

One or more embodiments provide a semiconductor component having reducedadverse influences in the electrically active region, a semiconductorwafer for obtaining semiconductor components having reduced adverseinfluences in the electrically active region, and a method for producingsuch semiconductor components.

The invention is characterized by the independent claims. Developmentsof the invention are found in the dependent claims.

One embodiment relates to a semiconductor component including asemiconductor body having an active region and a marginal regionsurrounding the active region, wherein the marginal region extends fromthe active region as far as an edge of the semiconductor body andwherein a zone composed of porous material is formed in the marginalregion. A further embodiment relates to a semiconductor wafer includingat least two semiconductor components each having an active region,wherein at least one zone composed of porous material is arrangedbetween the active regions of the semiconductor components.

A further embodiment relates to a method for producing a semiconductorcomponent, which involves providing a semiconductor wafer including atleast two semiconductor components each having an active region. Atleast one zone is composed of porous material is arranged between theactive regions of the semiconductor components. The semiconductor waferis separated between the active regions in order to produce individualsemiconductor bodies. The separation is effected in a separating zonealong the zone composed of porous material in such a way that eachindividual semiconductor body has an active region and a marginal regionsurrounding the active region. The marginal region extends from theactive region as far as an edge of the semiconductor body and wherein atleast one part of the zone composed of porous material remains in themarginal region.

One common element to these embodiments is that the zone composed ofporous material prevents the penetration of crystal defects from themarginal region, such as, for example, slip lines or dislocations causedduring the singulation of the semiconductor components, or else thepenetration of heavy metals into the electrically active region of thesemiconductor components. Consequently, the adverse influencing of theelectrical properties of the semiconductor component associated withsuch penetration of crystal defects or heavy metals into theelectrically active region is at least largely avoided. The penetrationof rapidly diffusing heavy metals into the electrically active region isprevented in one embodiment by a gittering of the heavy metals at thesemiconductor surfaces amply present in the porous layer.

Before the exemplary embodiments are explained in more detail below withreference to the figures, it is pointed out that identical elements inthe figures are provided with the same or similar reference symbols, andthat a repeated description of the elements is omitted. Furthermore, thefigures are not necessarily true to scale; rather, the main emphasis ison elucidating the basic principle.

FIG. 1 illustrates a schematic time view of a semiconductor body 10 of asemiconductor component. The semiconductor body 10 can be formed fromany monocrystalline semiconductor material. In one embodiment,monocrystalline silicon is suitable for this purpose. An active region11 is arranged in a region of the semiconductor body 10 that is arrangedcentrally in the plan view. An active region should be understood tomean that region of the semiconductor body 10 which carries current inthe operating state of a semiconductor component, or the semiconductorregion in which a space charge zone is established in the off state. Theactive semiconductor component structures of the semiconductor body 10are generally formed in the active region 11. Such active semiconductorcomponent structures include one or more junctions between differentlydoped semiconductor regions, such as, for example, pn junctions orregions having different dopant concentrations. By applying an externalvoltage to the active semiconductor structures with the aid of at leasttwo electrodes fitted to the semiconductor body 10, a current flowswithin the semiconductor component structures, which current can beregulated by control devices, such as, for example, a gate electrode inthe case of MOSFETs. The edge terminations of the pn junctions—such ase.g. field rings and/or field plates—also belong to the active region.

The active region 11 is surrounded by a marginal region 12, which has nospace charge zone in the blocking state. The marginal region 12 islikewise part of the semiconductor body 10 and extends from the activeregion 11 as far as an edge 13 of the semiconductor body 10.

A zone 14 composed of porous material is formed in the marginal region12. In the embodiment illustrated in FIG. 1, the zone 14 composed ofporous material is arranged exclusively in the marginal region 12 andspaced apart both from the active region 11 and from the edge 13.However, the zone 14 composed of porous material can also extendcompletely over the entire width of the marginal region 12 and possiblyeven partly project into the active region 11. Moreover, the zone 14 canalso extend in a manner spaced apart from the active region 11 as far asthe edge 13 of the semiconductor body 10 or from the active region 11 asfar as a specific distance from the edge 13. In this case, the zone 14composed of porous material has for example a width B in the range ofbetween 0.5 μm and 40 μm. The material of the porous zone 14 can be anydesired material that prevents penetration of crystal defects and heavymetals into the electrically active region of the semiconductorcomponent. By way of example, the material of the porous zone 14 canalso be a semiconductor material, in one embodiment the samesemiconductor material as the semiconductor body 10, such as silicon,for example. The porosity e of the porous material of the zone 14 shouldlie between 30% and 90%, in one embodiment between 50% and 85%. Theporosity ε is in this case defined as the ratio of cavity volume V_(H)to the total volume V:ε=V_(H)/V.

FIG. 2 illustrates a schematic cross-sectional view of an exemplaryembodiment of the semiconductor body 10 that is similar to the exemplaryembodiment in FIG. 1. The semiconductor body 10 once again has an activeregion 11, in which semiconductor component structures 15 are formed,and a marginal region 12, in which a zone 14 composed of porous materialis formed. The semiconductor component structures 15 are formed in thesemiconductor body 10 at a first surface 20 of the semiconductor body10. Moreover, a drift path D extends in the semiconductor body 10 fromthe semiconductor component structures 15 in the direction of a secondsurface 21 of the semiconductor body 10. In this embodiment, a driftpath is that part of the semiconductor body, for example of a powersemiconductor component, which takes up a space charge zone when areverse voltage is applied to the semiconductor component, proceedingfrom a pn junction. The drift path D is generally a lightly dopedsemiconductor region having a dopant concentration in the range of froma few 10¹³ up to a few 10¹⁵cm⁻³. The semiconductor body 10 has athickness d. A part of the active region 11 between the drift path D andthe second surface 21 can be used as a connection region 10 a for thesemiconductor component. The connection zone is highly doped in thisembodiment, that is to say that it has a dopant concentration of from afew 10¹⁷cm⁻³ up to a few 10¹⁹cm⁻³.

The zone 14 composed of porous material in the marginal region 12extends from the first surface 20 of the semiconductor body 10 rightinto a depth T into the semiconductor body 10 measured from the firstsurface. The depth T is dimensioned on the basis of the depth of theelectrically active region of the semiconductor body 10, that is to saythe depth of the maximum space charge zone occurring in the operatingcase of the semiconductor component into the drift path D in the activeregion 11 of the semiconductor body 10. In one embodiment, the depth Tshould be greater than the depth of the electrically active region inthe active region 11, that is to say for example deeper than the driftpath D, in order to prevent the penetration of crystal defects and heavymetals from the edge 13 into the electrically active region. In thisembodiment, the depth T lies for example in the range of between 2 μmand 250 μm. The depth T can also correspond to the thickness d of thesemiconductor body 10. This is tantamount to the zone 14 extendingcompletely through the semiconductor body 10.

The semiconductor component structures 15 in the active region 11 of thesemiconductor component, and also the entire active region 11 areelectrically connected to at least two electrodes 16 fitted to thesemiconductor body 10.

FIG. 3 illustrates a schematic plan view of an exemplary embodiment ofthe semiconductor body 10 wherein the zone 14 composed of porousmaterial extends over the entire width of the marginal zone 12. Theporous material thus forms the marginal region between the edge 13 andthe active region 11 down into the depth T. Consequently selecteddiffusion substances which can be used for example for channel stoppers,isolation diffusions or vertical edge terminations can indiffuse intothe active region 11 as required via the pores of the porous material.This is possible in one embodiment because the diffusion of selecteddopants or diffusion substances can take place significantly faster inthe porous material of the zone 14 than in the solid monocrystallinematerial of the semiconductor body 10.

FIG. 4 illustrates a schematic cross-sectional view of an excerpt of asemiconductor wafer 100. The semiconductor wafer 100 can be for exampleany customary wafer, which are currently obtainable with wafer diametersof up to 300 mm.

The semiconductor wafer 100 has at least two semiconductor components.Each of these semiconductor components formed in the semiconductor wafer100 has an active region 11 having semiconductor component structures15. At least one zone 14 composed of porous material is arranged betweenthe active regions 11 of the semiconductor components in thesemiconductor wafer 100. As already explained with regard to FIGS. 1 to3, the zones 14 can be produced from any desired porous material thatprevents propagation of crystal defects and heavy metal atoms. Ingeneral, the porous material of the zones 14 will be a semiconductormaterial, in one embodiment the same semiconductor material as that ofthe semiconductor wafer 100. The semiconductor wafer 100 has a thicknessd1. The zones 14 composed of porous material have a width B in thedirection from one active region 11 to the closest active region 11. Inthis embodiment, the width B lies in the range of 0.5 μm to 100 μm.Moreover, the zones 14 extend into the semiconductor wafer 100 from afirst surface 20 of the semiconductor wafer 100 as far as a depth T inthe direction toward the second surface 21 of the semiconductor wafer100, the second surface lying opposite the first surface 20.

FIG. 5 illustrates a schematic plan view of a semiconductor wafer 100.The semiconductor wafer 100 in turn has a multiplicity of semiconductorcomponents, wherein each semiconductor component has an active region 11and a zone 14 composed of porous material that surrounds the activeregion 11. In this embodiment, two zones 14 composed of porous materialare arranged alongside one another between two closest active regions11, the zones each having a width B. Between these two zones 14 lyingalongside one another, provision is made of a separating zone 30 alongthe zones 14. The separating zone 30 is that region in which thesemiconductor wafer 100 is separated for the singulation of thesemiconductor components. Consequently, the margin of the separatingzone 30 forms the later edge 13 of the semiconductor body 10 of asemiconductor component.

FIG. 6 illustrates a schematic cross-sectional view of an embodiment ofa semiconductor wafer 100 when the separating zone 30 is arranged in thezone 14 composed of porous material. This is tantamount to a single zone14 composed of porous material being produced between the individualactive regions 11 formed in the semiconductor wafer 100. The zone 14 hasa width B, however, which permits a separation of the semiconductorwafer 100 in the separating zone 30 and thus in the zone 14 and asufficiently wide residual zone 14′ composed of porous materialnevertheless still remains at the edge 13 of the semiconductor body 10of a semiconducting component produced in this way. In general,therefore, the width B of the zone 14 should in this case be greaterthan 20 μm. In the embodiment illustrated in FIG. 6, a semiconductorwafer 100 has a thickness d1. The zone 14 composed of porous materialextends only into a depth T adapted to the electrically active region ofthe active region 11. As an alternative, however, the zone 14 can alsoextend over the entire thickness d1 of the semiconductor wafer 100.

FIG. 7 illustrates a schematic cross-sectional view of a furtherembodiment of a semiconductor wafer 100 with zones 14 composed of porousmaterial. The semiconductor wafer 100 has an original thickness d1.Zones 14 composed of porous material are formed down into a depth T inthis semiconductor wafer 100. The zones 14 are situated between theactive regions 11 of the semiconductor bodies 10 of semiconductorcomponents that are arranged in the semiconductor wafer 100. After thezones 14 have been formed in the semiconductor wafer 100, thesemiconductor wafer 100 is thinned from its original thickness d1 to afinal thickness d2 at its second surface 21. In the example illustratedit holds true that the final thickness d2 is less than T. Consequently,the zone 14 composed of porous material extends over the entire finalthickness d2 of the thinned semiconductor wafer 100. The separating zone30 for separating the semiconductor wafer into individual semiconductorcomponents runs in the zones 14 composed of porous material in the sameway as already illustrated in FIG. 6. The zone 14 has to be formed witha width such that the width of the separating zone 30 is less than thewidth B of the zone 14. Consequently, a residue of the zone 14 composedof porous material remains between the edge 13 of the semiconductor body10 produced by the separation of the semiconductor wafer 100 and theactive region 11 and can thus achieve the desired effect that thepenetration of crystal defects and penetration of heavy metals into theelectrically active region of the semiconductor component are prevented.

FIG. 8 illustrates an exemplary embodiment of a semiconductor wafer 100wherein two laterally spaced-apart zones 14 composed of porous materialare formed between two active regions 11 in the semiconductor wafer 100and the separating zone 30 is provided between the two laterallyspaced-apart zones 14. The separating zone 30 thus runs in the solidsemiconductor material of the semiconductor wafer 100, as is alreadyknown in conventional methods for separating semiconductor wafers.Consequently, the singulation of the semiconductor components from thesemiconductor wafer 100 can be carried out with known process parametersof, for example, sawing or laser methods. An adaptation to themechanical properties of porous material such as is necessary forexample in the case of the exemplary embodiment concerning FIG. 6 orFIG. 7 is not required. On the other hand, it is possible to set theseparating speed through porous material generally to be higher than insolid material. Consequently, it would be possible to reduce the processtime for the singulation of the semiconductor components in the cases inwhich the separating zone 30 leads through the zone 14 composed ofporous material.

FIG. 9 illustrates a further exemplary embodiment of a semiconductorwafer 100 with zones 14 composed of porous material. Analogously to theexemplary embodiment concerning FIG. 8, in this case likewise two zones14 are arranged between the active regions 11 in the semiconductor wafer100 and the separating zone 30 runs between the two laterallyspaced-apart zones 14 composed of porous material. In contrast to theexemplary embodiment in FIG. 8, the semiconductor wafer 100, as alreadyexplained in the exemplary embodiment concerning FIG. 7, is thinned froman original thickness d1 to a final thickness d2.

FIG. 10 illustrates, in a further embodiment of the semiconductor wafer100, an arrangement of zones 14 composed of porous material and of theseparating zones 30 similar to the embodiment explained for FIG. 9. Incontrast to the exemplary embodiment in FIG. 9, additional zones 14 acomposed of porous material are formed in the semiconductor wafer 100.These additional zones 14 a can be arranged in direct proximity to thezones 14. However, the zones 14 a can partly overlap the zones 14 or bearranged in a manner laterally spaced apart from the zones 14. Theadditional zones 14 a can reduce stresses which arise in thesemiconductor wafer 100 for example during processing of thesemiconductor wafer 100 and lead to warpages of the semiconductor wafer100. The positioning of the additional zones 14 a in the semiconductorlayer 100 depends, for example, on where semiconductor regions are stillunused. The zones 14 a can be arranged on each individual semiconductorbody 10 of a semiconductor component or alternatively in one embodimentcompletely irregularly in the semiconductor wafer 100.

Finally, it should again be pointed out that the exemplary embodimentsillustrated are not intended to signify any restriction of the inventionto the examples specifically illustrated. Thus, by way of example, thethinning of the semiconductor wafer 100 or of the semiconductor body 10is dependent on the application sought for the semiconductor componentand has no influence on the specific lateral arrangement of the zones 14and the separating zones 30.

1. A semiconductor wafer comprising: at least two semiconductorcomponents each having an active region, and wherein at least one zonecomposed of porous material is arranged between the active regions ofthe semiconductor components.
 2. The semiconductor wafer of claim 1,wherein the zone composed of porous material extends from a firstsurface of the semiconductor wafer right into a depth T measured fromthe surface of the semiconductor wafer.
 3. The semiconductor wafer ofclaim 2, wherein the depth T corresponds to the thickness d1 of thesemiconductor wafer.
 4. The semiconductor wafer of claim 1, wherein thewidth B of the at least one zone composed of porous material in thedirection from one active region to the closest active region is between0.5 μm and 100μm.
 5. The semiconductor wafer of claim 1, wherein twozones composed of porous material are arranged between two closestactive regions.
 6. A method for producing a semiconductor component, themethod comprising: providing a semiconductor wafer as claimed in any ofclaims 15 to 19, separating the semiconductor wafer between the activeregions in order to produce individual semiconductor bodies, wherein theseparation is effected in a separating zone along the zone composed ofporous material in such a way that each individual semiconductor bodyhas an active region and a marginal region surrounding the activeregion, wherein the marginal region extends from the active region asfar as an edge of the semiconductor body and wherein at least one partof the 3 0 zone composed of porous material remains in the marginalregion.
 7. The method of claim 6, wherein the separating zone runswithin the zone composed of porous material.
 8. The method of claim 6,wherein the semiconductor wafer is separated between the two zonescomposed of porous material.
 9. The method of claim 6, comprisingindiffusing a dopant into the active region through the porous material.10. The method of claim 6, comprising thinning the semiconductor waferfrom an original thickness d1 to a final thickness d2 prior to theseparation.